There is the possibility of 'Browser Wars' re-erupting - but if they do, I don't see it repeating MSIE/Netscape, as there new features were introduced ad-hoc. There is more emphasis today on being standards compliant - and this is a good thing. I don't imagine that Google would want to promote non-standard html code, it'd make their core business more difficult - and so another standard compliant browser out there will be a kick to MSIE to get those remaining issues quashed (especially with CSS).

The bigger risk is google being too big, too powerful and breaking their 'don't be evil' motto (some would say 'too late'). Fingers in too many pies and all that. Whilst Chrome has the potential to squash all before it - I don't get that vibe at the moment. Let's see how things develop.